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AVL_Tree.java
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219 lines (172 loc) · 4.12 KB
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/*
Copyright 2020 Sakshi Khachane
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
public class AVL_Tree
{
//Declaring Node class
private class Node
{
int data;
Node left;
Node right;
int height;
public Node(int data)
{
this.data = data;
this.height = 1;
}
}
private Node root;
public void insert(int num)
{
this.root = insert(this.root, num);
}
//Display node Function
public void inOrder(Node node)
{
if (node != null)
{
inOrder(node.left);
System.out.print(node.data + " ");
inOrder(node.right);
}
}
//preorder traversal
public void preOrder(Node node)
{
if (node != null)
{
System.out.print(node.data + " ");
preOrder(node.left);
preOrder(node.right);
}
}
//post order traversal
public void postOrder(Node node)
{
if (node != null)
{
postOrder(node.left);
postOrder(node.right);
System.out.print(node.data + " ");
}
}
private Node insert(Node node1, int num)
{
if (node1 == null)
{
Node node2 = new Node(num);
return node2;
}
if (num > node1.data)
{
node1.right = insert(node1.right, num);
} else if (num < node1.data)
{
node1.left = insert(node1.left, num);
}
node1.height = Math.max(height(node1.left), height(node1.right)) + 1;
int balancefac = balancefac(node1);
// L-L Case
if (balancefac > 1 && num < node1.left.data)
{
return rightRotate(node1);
}
// R-R Case
if (balancefac < -1 && num > node1.right.data)
{
return leftRotate(node1);
}
// L-R Case
if (balancefac > 1 && num > node1.left.data)
{
node1.left = leftRotate(node1.left);
return rightRotate(node1);
}
// R-L Case
if (balancefac < -1 && num < node1.right.data)
{
node1.right = rightRotate(node1.right);
return leftRotate(node1);
}
return node1;
}
//Finding height of the node
private int height(Node num)
{
if (num == null)
{
return 0;
}
return num.height;
}
//Balance Factor
private int balancefac(Node num)
{
if (num == null)
{
return 0;
}
return height(num.left) - height(num.right);
}
//performing right rotation
private Node rightRotate(Node node3)
{
Node node4 = node3.left;
Node node = node4.right;
node4.right = node3;
node3.left = node;
node3.height = Math.max(height(node3.left), height(node3.right)) + 1;
node4.height = Math.max(height(node4.left), height(node4.right)) + 1;
return node4;
}
//performing left rotation
private Node leftRotate(Node node3)
{
Node node4 = node3.right;
Node node = node4.left;
node4.left = node3;
node3.right = node;
node3.height = Math.max(height(node3.left), height(node3.right)) + 1;
node4.height = Math.max(height(node4.left), height(node4.right)) + 1;
return node4;
}
public static void main(String[] args)
{
AVL_Tree tree = new AVL_Tree();
tree.insert(10);
tree.insert(20);
tree.insert(30);
tree.insert(40);
tree.insert(50);
tree.insert(25);
System.out.println("Preorder display: ");
tree.preOrder(tree.root);
System.out.println("\n\nInorder display: ");
tree.inOrder(tree.root);
System.out.println("\n\nPostorder display: ");
tree.postOrder(tree.root);
}
}
/* Input:
* 10 20 30 40 50 25
*/
/*
* Output:
*
* Preorder display:
30 20 10 25 40 50
Inorder display:
10 20 25 30 40 50
Postorder display:
10 25 20 50 40 30
*/